148 Mr. C. Spence Bate on British Edriophthahnous Crustacea. 



Genus 4. Podocerus* (Leach). 



Upper antenna with a rudimentary second filament. Lower 

 antenna pediform, and terminating in strong spinous hooks. 

 Posterior pleopoda with one branch styHform, the other termi- 

 nating in hooks. 



Construct nests. 



1. P. falcatus (Montagu). Hand of the second gnathopod large^ 



with a tooth pointing anteriorly in the middle of the palm. 

 Plymouth ; Wales, C. S. B. Devon, Montagu. 



2. P. variegatus (Leach). Hand of second gnathopod large, 



without a tooth on the palm. 

 Plymouth, C. S. B. Bell Rock, Stevenson {White's Catalogue 

 of the British Crustacea) . 



8. P.pulchellus (Leach). Hand of second gnathopod large, with a 

 well-developed thumb at the posterior extremity of the palm. 

 Plymouth, H. Stewart, Esq., C. S. B. Swansea, C. S. B. Banfi", 

 Mr. Edwards. 



4. P.punctatus (Edwards, MS. Brit. Mus.). Antennae subequal ; 

 inferior not pediform. Carpus of the gnathopoda forming 

 part of the hand. Dactylos on all the limbs denticulated. 

 Telson rudimentary. 

 Northumberland, /. Alder, Esq. 



Genus 5. Cyrtophium (Dana). 

 Pereion inflated ; pleon compressed. Posterior pleopoda rudi- 

 mentary. Telson squamiform. 



1. C. Darwinii. Dorsal surface imbricated. First of the posterior 

 pleopoda longer than the second. 

 Falmouth, W. Webster, Esq. 



Section IL Tubijica. 



Dwell in tubes, some formed by burrowing, some constructed 

 by the union of materials. 



Subfamily II. CERAPIDES. 

 Construct abodes by the union of materials. 



Genus 6. Ericthonius (Edwards). 

 Lower antenna not pediform. Thumb developed on carpus of 



* It is usual to divide this genus into two, Podocerus and Jassa, but there 

 is great reason to believe that the dilFerence is merely sexual. It is evi- 

 dently synonymous with Dana's genus Cratophium ; the species C. validum 

 being almost identical with P. pulchellus. 



